U.S. Geological Survey Fact Sheet 152-00
Online Version 1.0

The image above shows car-sized bubbles of lava from a lava-formed "bench" at the water's edge. Ocean water enters the lava tube, flashes to steam, and blows through the roof of the tube. The image to the left shows an explosive fountain throwing hot lava spatter and basket-ball sized rocks 300 feet (100 m) in the air; the fountain resulted when a piece of a lava-filled bench collapsed and exposed hot rock into the ocean.

The current eruption of Kilauea Volcano began in 1983 with spectacular lava fountaining at a new vent, named Pu‘u ‘O‘o, high on the volcano's east rift zone. Although surface flows have been common in this eruption, most of the lava from the vent travels concealed in lava tubes until it reaches the ocean. 

When lava moves through the landscape and into the ocean, we see how the Hawaiian Islands are built. The experience of witnessing rock in its bright molten state and watching land being formed has fascinated and inspired everyone who has been lucky enough to see it. Seeing lava for the first time is captivating and often lures the viewer closer, but it is also beguiling and dangerous. 

When hot lava enters the water, it bursts into pieces, building new land at the ocean edge from the fragmental material. This pile of rubble is then covered with a veneer of lava flows, forming a "bench" that gives a false impression of solid ground. 

Without experience drawn from years of watching the behavior of this volcano, the casual visitor cannot know all the hazards and may easily underestimate them. Unfortunately, warning signs cannot always be posted near hazardous areas. This is because the positions of lava flows and lava tubes change frequently. 

The information in this pamphlet has been gathered from the experiences of Earth scientists working on Kilauea. Heeding its lessons can help you safely enjoy your visit.

Formation of bench and unstable land
	An area of new, unstable land, commonly called a "bench", forms where the lava enters the ocean. Although most activity consists of sluggish submarine flows and mild spattering, sudden landslides can cause the bench to collapse and trigger violent explosions that throw lava and rocks 300 feet (100 m) inland.
	This lava covered bench looks solid from above but can collapse unexpectedly. Be alert to cracking or booming sounds.
	Such collapse can trigger a series of strong explosions that blasts lava spatter and large rocks and send waves of scalding water onshore.
	This lava covered bench looks solid from above but can collapse unexpectedly. Be alert to cracking or booming sounds.

Is the water hot near ocean entry sites of lava?

In 1994, two people standing near the water's edge at an ocean entry site of lava were caught off guard by a sudden wave. They were severely scalded and had to be hospitalized. 

When hot lava touches the ocean, it evaporates some water, forming an impressive steam plume, and heats the surface water to temperatures capable of causing third-degree burns. Visitors should stay away from the water near the bench, because unexpected waves from natural tides or high surf, as well as from sudden bench collapses, can splash hot water onto shore!

Why are steam plumes considered a hazard?

Avoid walking under plumes of "laze" (lava haze) formed when hot lava makes seawater boil and vaporize. Chloride in the sea salt combines with hydrogen in the water to form hydrochloric acid in the plumes. Clouds of laze produce "acid rain," which can fall on people and land along the coast during onshore winds. The rain, with a pH between 1.5 and 3.5 (pure water has a neutral pH of 7), has the corrosive property of battery acid. The plume cloud also contains tiny glass fragments that can irritate the eyes and, in rare cases, cause permanent damage. 

Avoid walking under steam plumes!

Onshore winds can blow the steam plume from lava entering the ocean into the path of hikers, creating a whiteout. This plume hides deep cracks in the middle ground of the photograph.

What is a "whiteout"?

Onshore winds can blow steam plumes onto the land, causing visibility to be limited. This can be disorienting and could cause you to walk into risky areas. Move away from a whiteout when the winds shift. 

Heavy rain can also produce dense fog that limits visibility.

What is "vog" and who is at risk breathing it?

"Vog" (volcanic smog) is the visible haze that forms when irritating sulfur dioxide and other volcanic gases combine and interact chemically with oxygen, moisture, dust, and sunlight. Kilauea emits about 2,000 tons of sulfur dioxide each day during eruption, now mainly from the still-open vent at Pu‘u ‘O‘o. 

Trade winds commonly disperse the volcano's gases, so that the concentration is not generally hazardous. However, sulfur dioxide fumes can be concentrated near ground cracks along and down-wind from lava tubes. 

Concentrated sulfur dioxide fumes put all people at risk, but particularly those persons with breathing problems (such as asthma and chronic obstructive pulmonary disease) and heart difficulties, pregnant women, infants, and young children. If sulfur-fume concentrations begin to cause you physical distress, you should leave the area.

The current eruption of Kilauea, which began in 1983 at Pu‘u ‘O‘o on the volcano's eastrift zone, has covered many square miles with lava flows and added new land along the Island of Hawai'i's south coast. Insert shows a 1986 high-fountaining event at Pu‘u ‘O‘o. Such fountaining built a cone 835 ft (255 m) high, but the cone has lost much of its to because of collapses since 1986.

Typical irregular surface of pahoehoe. Red glowing areas in the foreground show that this flow is still active.

How long does it take to walk there?

The hummocky surfaces of pahoehoe lava flows are unlike anything most people have walked on. Because of their surface irregularities, you should allow twice the time you think the walk might take. If a ranger tells you it is 3 miles (5 km) to the flows, consider it the equivalent of walking 5 to 6 miles (8-10 km) on a smoother surface. (Also, don't forget that the return trip always seems twice as long!)

I am only going for a few hours. Why do I need a flashlight?

Many people who walk out just for a day hike get caught in the dark. This can happen because (1) they didn't estimate their speed properly, (2) they were engrossed in the scenery and didn't pay attention to the time, or (3) darkness falls more quickly near the equator than in temperate locales; when the sun sets, there is less than an hour of twilight left.

WHAT IS A SKYLIGHT?

A scientist from the Hawaiian Volcano Observatory probes into a lava tube through a "skylight" near the coast. Lava in the tube has a temperature of about 2,120°F (1,160°C). The steam plume in the background is created where lava from this tube reaches the ocean. Large volumes of lava commonly travel in lava tubes beneath the congealed surface of recent flows. "Skylights" form when the roof of a lava tube collapses, revealing the molten lava flowing beneath. It is important to stand well back from these holes, which form where the roof of the tube is thin and unstable.

What do I need to take with me when I visit the lava-flow field?

Shown below are the items that the National Park advises taking when visiting the lava-flow field. They are arranged from the essential ("very important") items at the top to recommended items at the bottom. 

No services are available at the end of Chain of Craters Road. Purchase any needed items before you drive to this area.

Isn't some of this equipment unnecessary?

Most injuries are not directly due to the eruption. Intense sunlight and high temperatures can lead to dehydration, heat exhaustion, or sunstroke. Take sunscreen and a hat and drink more water than you think you need. Air temperatures near lava flows can exceed 120°F (49°C), depending on cloud cover and wind conditions. At higher elevations, wind and rain can chill you and lead to hypothermia (low body temperature). 

Injuries from falling are common. It is easy to break through a thin, overhanging crust of lava or trip on a crack and fall on the abrasive, glassy surface. U.S. Geological Survey (USGS) scientists always wear long pants, sturdy boots, and sometimes gloves when working near the flows-never shorts and slippers!

Before trying to visit the lava field, check with Park Rangers for current conditions there and for the best approach route. Park Rangers do not recommend that you attempt the hike to the coast if you are unprepared or uninformed. The area is remote, has no shade or water source, and is seldom patrolled.

By informing the public about hazards in Hawai'i Volcanoes National Park, the USGS and the National Park Service help visitors safely enjoy the park's attractions. The work of the Hawaiian Volcano Observatory is part of the U.S. Geological Survey's efforts to understand volcanoes and help protect people's lives and property from volcano hazards in all of the volcanic regions of the United States, including Hawai'i, Alaska, Wyoming, California, and the Pacific Northwest.

Jenda Johnson